The changes in 0.29.1 center on the treatment of --variable
and --define_variable.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

Buildbots reported build failures when full NLS is enabled:

http://buildbot.openwrt.org:8010/broken_packages/ar71xx/pkg-config/compile.txt

So add NLS awareness and the conditional dependency.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

pkg-config is a helper tool used when compiling applications and libraries.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

[Fixed trailing whitespace in package description.]

Signed-off-by: Michael Heimpold <mhei@heimpold.de>